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Description

We consider the design of information-theoretically secure techniques for key management (i.e., generation/agreement and replacement/update) over stochastic channels. Such keys may be used to enable secure communications over otherwise insecure and open channels. As such, we consider the agreement (update) of a secret key as a proxy for the establishment (maintenance) of secure communications. This problem space is relevant for networks whose communication links have unreliable quality or availability (e.g., tactical mobile ad-hoc networks). In such environments, existing key management techniques such as public key servers or key pre-distribution become too expensive, risky, or slow.

The thrusts of this research are as follows: (1) the characterization of the tradeoff space between key agreement rate, secrecy, and delay; (2) the analysis of the division of fresh entropy across key agreement and key update; and (3) techniques for key agreement and update over a network with highly-constrained channels.

An interesting opportunity arises in noisy channels because the requirements for perfect secrecy are different than those for noiseless channels. In fact, it has been shown that as long as the channels to the friendly and attacker parties are different, it is possible to agree on a key that is perfectly secret from the attacker. This secret key may then be used in a variety ways such as enabling perfectly secret communication (e.g., in a one-time pad) or authenticating over open channels (e.g., fingerprinting). One of the major obstacles in applying these concepts for tactical networks is the need for many rounds of communications over an open channel. For the networks of interest, this open channel has limited availability and bandwidth.